For service and diagnostic purposes, machines are sometimes equipped with sensors for measuring operating conditions such as engine RPM, oil pressure, water temperature, boost pressure, oil contamination, electric motor current, hydraulic pressure, system voltage, and the like. In some cases, storage devices are provided to compile a data base for later evaluation of machine performance and to aid in diagnosis. Service personnel examine the accrued data to get a better picture of the causes of the failure or to aid in diagnosis. Similarly, service personnel evaluate the stored data to predict future failures and to correct any problems before total component failure.
In addition, these stored parameters may be examined by service or supervisory personnel to evaluate machine and/or operator performance to ensure maximum productivity of the machine. These issues are particularly pertinent to over-the-highway trucks and large work machines such as off-highway mining trucks, hydraulic excavators, track-type tractors, wheel loaders, and the like. These machines represent large capital investments and are capable of substantial productivity when operating. It is therefore important to predict failures so servicing can be scheduled during periods in which productivity will be less affected and so minor problems can be repaired before they lead to catastrophic failures.
Similarly, it is sometimes advantageous to accumulate parameters only when the machine is in a particular operating condition. This type of information is predominantly used during performance evaluation but may also be used in failure diagnosis and prognosis. For example, the length of time spent in a particular gear while the machine is loaded may be needed to evaluate machine performance.
The present invention is directed to overcoming one or more of the problems set forth above.